title: Arm raising at exposure-controlled multidetector trauma CT of thoracoabdominal region: higher image quality, lower radiation dose.
abstract: OBJECTIVE
  To evaluate the effect of arm position on image quality and effective radiation dose in an automatic exposure-controlled (AEC) multidetector thoracoabdominal computed tomography (CT) protocol in trauma patients.
  
  
  METHODS
  This retrospective study of the data of 177 trauma patients (117 male; median age, 39 years) was approved by the institutional ethics board, with informed patient consent waived. Patients underwent scanning by using an AEC 16-detector thoracoabdominal CT protocol in which both arms were raised above the shoulder region (standard-position group, 132 patients), one arm was raised and the other was down (one-arm group, 27 patients), or both arms were down (two-arm group, 18 patients). Objective and subjective image quality was assessed. Individual effective radiation dose was calculated from the effective tube current-time product per exposed section. For this purpose, section location-dependent conversion factors were derived by using a CT dosimetry calculator. The effect of arm position on effective dose was quantified by using linear regression analysis with correction for patient volume and attenuation.
  
  
  RESULTS
  Compared with the image quality in the standard-position group, the image quality in the one- and two-arm groups was decreased but within acceptable diagnostic limits. The median corrected effective dose in the standard-position group was 18.6 mSv; the dose in the one-arm group was 18% (95% confidence interval: 11%, 25%) higher than this, and that in the two-arm group was 45% (95% confidence interval: 34%, 57%) higher.
  
  
  CONCLUSIONS
  Omitting arm raising results in lower but acceptable image quality and a substantially higher effective radiation dose. Hence, effort should be made to position the arms above the shoulder when scanning trauma patients. Clinical trial registration no. NCT00228111.
authors.affiliation: Department of Diagnostic Imaging, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands. M.Brink@rad.umcn.nl
authors.forename: Monique
authors.initials: M
authors.lastname: Brink
authors.forename: Frank
authors.initials: F
authors.lastname: de Lange
authors.forename: Luuk J
authors.initials: LJ
authors.lastname: Oostveen
authors.forename: Helena M
authors.initials: HM
authors.lastname: Dekker
authors.forename: Digna R
authors.initials: DR
authors.lastname: Kool
authors.forename: Jaap
authors.initials: J
authors.lastname: Deunk
authors.forename: Michael J R
authors.initials: MJ
authors.lastname: Edwards
authors.forename: Cornelis
authors.initials: C
authors.lastname: van Kuijk
authors.forename: Richard L
authors.initials: RL
authors.lastname: Kamman
authors.forename: Johan G
authors.initials: JG
authors.lastname: Blickman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001132:Arm / Q000502:physiology*; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology*; D011829:Radiation Dosage; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014949:Wounds, Nonpenetrating / Q000000981:diagnostic imaging*